WASHINGTON — Senator Lindsey Graham said Monday the FBI told him it was initially unaware Tamerlan Tsarnaev had traveled to Russia early last year because of a clerical error: His name was misspelled.

“He went over to Russia, but apparently, when he got on the Aeroflot plane, they misspelled his name,” Graham, a South Carolina Republican, said on Fox television. “So it never went into the system that he actually went to Russia.”

Federal officials did not respond to requests to independently confirm Graham’s account, and his office did not respond to several follow-up requests for fuller context.

Members of the Massachusetts congressional delegation and homeland security specialists cautioned that the full facts of Tsarnaev’s six-month stay in Russia have not yet surfaced. But they said Graham’s account raises questions about potential holes in the system for screening international travel and for linking databases so that all potential dangers involving individuals are in one place.

The system has been upgraded significantly since the Sept. 11, 2001, attacks but continues to be refined.

“How did he travel to Russia? Is it a sufficient system to let us know how people travel on green cards?” said Representative Michael E. Capuano, a Somerville Democrat. “Those are all good questions.”

Representative William R. Keating, a Bourne Democrat who sits on the House Committee on Homeland Security, said he was assured his committee would receive briefings and hold hearings.

“That’s going to be addressed in detail, because that’s the kind of issue that’s important to find out the actual and the full facts,” Keating said.

Tsarnaev, the 26-year-old terrorism suspect who died Friday after a shoot-out with law enforcement officers, had been flagged in 2011 as a potential danger by Russian authorities. Graham, who on Sunday criticized the FBI’s 2011 response, said he was told by its deputy director Sunday night that agents interviewed Tsarnaev, his parents, and his schoolmates and did a thorough records search but found no evidence of a threat.

Graham, a member of the Senate Armed Services Committee, said on Fox that he did not know if Tsarnaev had misspelled his name on purpose during his trip to Russia.

Graham did not specify where the name was misspelled or whether information from Tsarnaev’s Kyrgyz Republic passport, his US permanent resident identification card, and US Customs and Border Protection information made it into government records.

There have been previous cases of mistaken identity involving terrorists, including the case of Umar Farouk Abdulmutallab, who tried to set off an explosive in his pants on a US-bound airliner on Christmas 2009. Due to a series of clerical errors made by the Department of State, including the spelling of his name on his US visa, the Nigerian terrorist was not placed on a watch list, as the FBI had requested, and boarded a jetliner headed for Detroit.

Airlines play a key role in border protection. They are responsible for providing lists of passengers and passport numbers for flights in and out of the country. Agents review those lists to determine if flights need to be held or passengers need additional screening, said Christian Beckner, who until January served as associate staff director for the Senate Homeland Security and Governmental Affairs Committee.

There has been at least one other variant spelling of Tsarnaev’s family name. His uncle Ruslan, who lives in Maryland, spells it “Tsarni.” And Capuano and others noted the Cyrillic alphabet used in Russia is difficult to transliterate consistently into English.

Tsarnaev’s identity also should have been linked to his name through his fingerprints, which should have been recorded when he was charged with domestic violence in 2009, and which should have been taken again when he returned from Russia, Beckner said.

In addition, Tsarnaev’s green card should have been scanned by federal officials when he returned to the United States, said Beckner, now deputy director of the Homeland Security Policy Institute at George Washington University.

Even though Tsarnaev was vetted by the FBI in 2011, he would not necessarily have been placed on a terror watch list. Security officials probably kept him off when the FBI failed to turn up corroborating evidence of terrorist activity, Beckner said. The mere fact that a foreign government reports someone as a threat is not enough to put the person on a terror listing, he said, because that could invite foreign governments to retaliate against dissidents by falsely reporting them to the United States.

But the Russian contact could have been the basis for putting Tsarnaev’s name on another type of lower-tier list. And federal investigators will want to find out whether that list would have or should have been linked to immigration records, specialists said.

“I’m sure the FBI is scrambling to do a review,” said Todd Harrison, former chief of the terrorism division in the US attorney’s office in New York. He prosecuted two Pakistani-Americans who conspired to plant bombs on the New York subway system.